Food intakes and weight changes in climatic extremes.

Nutrition and physical performance 113 I have to repeat again, and apologize for, my inability to give much indication of the effect of ageing on total daily energy expenditure. We have, however, seldom found much obvious difference between the mean values for comparable populations ; the mean energy output of sedentary men aged about 60 we have measured as about 2600 kcal/day, which is similar to values found for young men. Our elderly forestry workers expended over 3500 kcal/day, and the farmers over 3500 kcal/day. Several individuals reached levels of up to 4500 kcallday although none of our Scottish subjects approached the 5000 kcallday of one of the elderly Swiss peasants we studied. From our measurements on women, a small effect of age on energy output seems obvious. T h e mean values are usually low for all age groupings, means of 2200 kcallday for young women comparing with 2100 kcal/day in middle-aged women and about 2000 kcal/day in the elderly. The upper limit of the range is very much lower for elderly women than for men, 3000 kcal/day being the maximum we have seen in Scotland; I hesitate to say that we obtained a value of 3900 kcallday for a Swiss peasant woman. I have only scratched the surface of this problem of age and physical activity. It is an interesting problem and likely to have much medical and sociological significance. It would be pleasant to think that the accumulation of new experimental information might induce the Society to repeat this Symposium in a few years time.